Replaceable pile sleeve insert



July 29, 1969 c. POGONOWSKI REPLACEABLE FILE SLEEVE INSERT 3 Sheets-Sheet 1 Filed March 26, 1968 July 29, 1969 a. c. POGONOWSKI REPLACEABLE FILE SLEEVE INSERT 3 Sheets-Sheet 2 Filed March 26, 1968 7 1A J 4 a W W, 00 M w A 5% m mw 2 m V i 4 w J /5 E. 7 1 ill W J W A: T

July 29, 1969 c. POGONOWSKI 3,457,728

REPLACEABLE PILE SLEEVE INSERT Filed March 26, 1968 United States Patent 3,457,728 REPLACEABLE PILE SLEEVE INSERT Ivo C. Pogonowski, Houston, Tex., assignor to Texaco Inc., New York, N.Y., a corporation of Delaware Filed Mar. 26, 1968, Ser. No. 716,042 Int. Cl. E021) 17/00; E02d 5/22, 21/00 US. Cl. 6146.5 13 Claims ABSTRACT OF THE DISCLOSURE The invention relates to an elongated composite leg and stub pile structure for supporting an offshore drilling platform above the water surface. The leg comprises an outer casing enclosing a plurality of guide tubes to receive one or more piles which extend to and penetrate the sea bottom. An expendable collar functions as an extension to the respective guide tubes, and includes a rigid joint at which the pile and guide tube overlap.

BACKGROUND OF THE INVENTION Progressive advances in oil drilling and producing technology dictates that of necessity, such future operations will be extended to a greater extent to offshort installations. Further, the many sources and possibilities for productive offshore wells require that such wells be located in water depths up to and exceeding 1,000 feet.

At present, under water techniques and available equipment often render deep well drilling operations expensive and highly impractical. Not only is the equipment for such work undeveloped, but the labor cost for deep Work is virtually prohibitive.

In the instance of a drill platform positioned above the water surface there need be little variation from the type of platform that is now used. However, for the supporting structure to safely accommodate either a stationary or a jack-up type platform, requires special characteristics. Today, the usual support leg structure comprises in general either an open lattice-like member or a closed cylindrical unit. In either instance the length of the leg is not excessive and can be used in water depths up to 200 or 300 feet. Jack-up legs of course not only must be adequate to support a predetermined load, they must also embody structural rigidity to be self-supporting when extended upward from the platform in the normal withdrawn position.

As a matter of practicality, a support leg for use in water depths approximating 1,000 feet, and capable of extending into the air from the platform either for initial assembly or for subsequent moving, would assume gargantuan proportions. This adds not only to the weight of such a support but also to the cost. Further, the problem of anchoring such support legs as by the usual piling technique is compounded. For example, as the pile length is increased the pile driving mechanism becomes less eflicient since with the added pile length, a greater amount of the hammering energy is absorbed in the pile rather than utilized for advancing the pile. Another detriment to the use of elongated piles is the propensity for the column to flex during the driving operation thereby lessing the effective impact of the driving hammer.

3,457,728 Patented July 29, 1969 "ice A further consideration of no minor proportion is the desirability of salvaging as much as possible from a nonproducing installation for use on a subsequent offshore platform. To be feasible, the salvage operation must be both practical and also preserve the parts for such future use. It is understandable then that a structural unit approximating 1,000 feet in length requires special handling in view of the lack of equipment or the impracticality of equipment to handle such proportionately large members.

It is therefore an object of the invention to provide a novel form of platform leg particularly for offshore use that is not only structurally adequate but is also salvageable. A further object is to provide a composite platform support leg particularly adapted for a jack-up installation and combining a plurality of piles as internal support members. A still further object is to provide a unique leg structure embodying a plurality of dissimilar structural members so connected as to facilitate disassembly thereof. Another object is to provide a platform support leg of the type described in which an expendable portion is utilized to unite dissimilar structural members thereby permitting maximum salvaging of the entire unit.

DESCRIPTION OF DRAWINGS In the drawings FIGURE 1 illustrates the present composite platform supporting leg imbedded in the ocean floor to support a drilling platform above the water surface. FIGURE 2 is a cross-sectional view on an enlarged scale of a portion of the support leg shown circled in FIG- URE 1. FIGURE 3 is an alternate embodiment of the platform support leg illustrating the unitizing joint between the piling and pile guide tube. FIGURE 4 is another alternate embodiment of the platform support leg structure illustrating the connection between pile and pile guide tube. FIGURE 5 is an alternate embodiment of the structure shown in FIGURE 4, and FIGURE 6 illustrates a further embodiment of the removable connection between the composite leg casing and piling.

The invention in brief comprises an elongated leg structure for supporting a drilling platform in a deep Water location such as the ocean. The leg comprises essentially an outer casing which depends downwardly from the platform toward the ocean floor. A plurality of guide tubes are disposed within the casing and extend longitudinally thereof for at least a portion of the casing length. The respective guide tubes connect to the casing wall and function as lateral support members. Each guide tube is adapted to receive a pile, to guide the same during the driving operation, and also to laterally support the pile upper end for transferring load forces from the pile to the casing. One or more disposable collars are carried on each composite leg as an extension to the respective guide tubes through which a pile passes. Each collar includes means for fixedly positioning the pile and guide tube, thereby to form a rigid, non-flexing joint. The collar is also positioned to be readily removed and facilitate a salvage operation whereby the leg casing and the piles are readily separated.

FIGURE 1 illustrates an offshore drilling installation in relatively deep body of water wherein drilling platform 10 is supported above the surface of the water. The platform accommodates the usual derricks, draw-works, rotary table and other equipment ancillary to a drilling op eratioirsThe platform; as 'is well known, may be supported at the ocean floor by one or more legs which supportably fasten to the platform. While the number of legs applicable to a particular installation can vary with the size of the platform and depth of water, the presently described leg structure would still be appropriate. However, for the purpose of the following description a four-legged unit is shown wherein the platform is essentially rectangular having a composite jack-up type leg 11 operably situated-at'each corner.

Leg 11 comprises an elongated casing 12 generally cylindrical in cross-sectional configuration and formed of a plurality of end welded lengths of pipe or tubing. The thickness of the casing wall can vary in accordance with the strength requirements dictated by such factors as soil characteristics, water depth, and platform load. A plurality of guide tubes 13 are disposed in casing 12 extending for at least a part of the casing length and terminating adjacent the casing lower end.

A pile 14 is positioned in and extends from the respective guide tube ends. Said piles number as many as is deemed necessary for the purposes of anchoring and also for adequately supporting the platform. Piles 14, reaching to the ocean floor, are imbedded for a suflicient length to firmly anchor the leg '11 and platform 10. The depth to which the individual piles are imbedded is contingent on the condition of the ocean floor, that is whether the latter be basically of a sandy nature, clay type formations or other composition.

One embodiment of the novel leg structure is shown in FIGURE 2 and comprises casing 21 which as mentioned is constructed at its upper end to operatively or stationarily engage clamping mechanism at platform 10. The casing comprises heavy walled tubing or pipe which for the depth under consideration, could be 8 to feet in diameter tubing which is end welded to make up the overall casing length required.

Guide tubes 22 and 23 are positioned within casing 21 extending in a longitudinal direction. The lower end of the respective guide tubes terminate adjacent the casing lower end. In the present arrangement, tubes 22 and 23 are welded to a lower closure plate 24. Plate 24 may comprise a solid member transversing the casing lower end. In the alternative it may merely comprise a reinforced support structure having a plurality of receiving hubs 26 and 27 into which the respective guide tube ends are welded.

Guide tubes 22 and 23 are spaced apart within the interior casing 21. However, the exact number of tubes which may be received in a casing is variable. The respective tubes may further be of such a diameter as to be retained in longitudinal abutting contact thereby affording a. mutual rigidity to each other as well as to the casing 21.

When spaced apart, the respective guide tubes 22 and 23are positioned with respect to each other and with respect to] the casing inner wall by longitudinally spaced reinforcing braces 28. Brace 28 may comprise an open framework adapted to engage the respective guide tube to impart the reinforcing rigidity. Said member may also assume the form of a watertight bulkhead to which the guide tubes are welded if the casing is to be compartmented into flotation chambers which might also function as oil storage facilities.

Guide tubes 22 and 23 need not extend the entire length of casing 21. They are however of sufiicient length beyond the lower end of casing 21 to enclose a length of the internally positioned pile 31 and rigidize the latter against bending stresses.

Closure plate 24 includes a plurality of through openings 29 in alignment with the central openings in hub 26 and guide tube 22. Pile 31 is formed in a manner well known with respect to such anchoring devices and includes a relatively heavy wall tubing adapted to be driven into the ocean floor to a predetermined, or an undetermined depth. As shown in FIGURE 1 the upper end of pile 14 which corresponds to pile 31 in FIGURE 2, extends upwardly of the top edge of the casing 11 to accommodate a driving hammer or other device which is supported above the pile. The length of pile adaptable to be used is of course governed within the limitation of the diameter of the same as to avoid the contingency of pile buckling or flexing either during the driving operation or as a support member.

Referring again to FIGURE 2, pile guide tube 22 extends through the casing to be both a physical guide during insertion of pile 31 and to subsequently laterally support the same for a portion of its length within the casing. The outside diameter of pile 31 is therefore such as to be spaced slidably from the inner wall of tube 22 to permit a sliding fit therebetween. Thus, buckling of the pile will be minimized or even completely precluded during the driving operation.

The lower end of casing 21 is provided with removably connected elongated collars 32 and 33. While the present description suggests the use of only two such collars it is understood that the collars will correspond to the number' of piles used in a particular leg structure. Collar 32 includes a flange 30 from which depends a cylindrical body 34. Flange 30 is provided with circularly arranged bolt holes to accommodate bolts 36 which fasten the flange to the lower side of closure plate 24. A resilient gasket or spacer 37 is deformed between flange 33 and plate 24 to facilitate removal of collar 32 in spite of the latter having been submerged in sea water for a prolonged period of time.

A primary function of collar 32 is to fixedly position, both laterally and longitudinally, pile 31 with respect to casing 21. This is achieved at an annular joint within the collar comprising a material such as cement which is hardened within annulus 38 to define elongated tight connection between the collar and pile walls. This means of making a pile connection is widely known and used. Further the use of longitudinally spaced resilient rings 39 and 41 is often utilized for confining the cement joint length to a required length.

Resilient rings 39 and 41 are fixed to the inner wall of body 34 and formed of a pliable material subject to deformation and yet adapted to form a peripheral seal to retain concrete or other hardenable media. Thus, as pile 31 is lowered or driven through collar 32, the pile will slidingly engage the respective seal rings 39 and 41. Subsequently, when the pile is fully imbedded to anchoring depth, rings 39 and 41 will define with the respective collar and pile, closed end annulus 38 for receiving the hardenable sealing material. It should be mentioned that the spacing between said rings 39 and 41 is sufficiently long as determined through engineering standards to form a firm sealing relationship between the pile and the collar 32.

With the pile firmly seated in place at the ocean floor, the connecting joint at annulus 38 is formed by introducing fluidized sealing material such as cement from the water surface through line 43 and inlet 42 which connects to the annular space 38. Rising of the cement through the annulus is limited by the upper ring 39, the excess cement thereafter passing through the riser line 44 by way of outlet 46. Alternatively, the cement seal might be applied in a suflicient amount to just form the annulus, said amount being determined by suitable measuring means associated with the collar at annulus 38. As herein mentioned the pile 31 is normally in sliding engagement with the guide tube 22. However to form an adequately thick seal at annulus 38, the inner diameter of collar 32 is increased beyond the diameter of the guide tube 22 in an amount to achieve the necessary wall thickness of the seal.

The lower end of body 34 opens into the ocean whereby pile 31 may pass thereto. The upper end of collar 32 is fastened by bolting or other means to plate 24. However, it is appreciated that an adequate fastening of the collar to the casing lower side may be achieved by suitable means such as a clamping arrangement. For example and referring to FIGURE 6, a similar casing 21 is there shown including guide tube 22 as is described with relation to FIGURE 2. The numerical designations in FIG- URE 6 correspond essentially to those simiarly designated in FIGURE 2 to aid in the following description.

In the latter, and referring to FIGURE 6, closure plate 24 at the lower side of casing 21 is provided along its outer surface with a circular boss 51 having a center aperture in alignment with opening 29. Boss 51 includes a radially protruding clamping ring 52. The dimensions of clamping ring 52 correspond substantially with the dimensions of collar flange 30 that the circular, removable clamp 53 might be tightened about the ring and flange to bring mating surfaces thereof into pressed engagement with spacer 37.

One notable advantage of a clamped connection between collar 32 and casing 21 is that the collar can be rapidly disconnected from the lower side of casing 21. Particularly if the operation is achieved under water, the operation time would by necessity have to be brief in accordance with the water depth. Thus, whether collar 32 is used either under water or at the surface, clamp 53 is readily adapted to the connection for permitting removability of the collar.

For example, collar 32 is normally fastened to casing 21 at plate 24 prior to the casing being lowered into a body of water as a step in the platform positioning. Pile 31, or more accurately the pile lower end is prepositioned 'in guide tube 22. With leg 11 lowered from platform 10,

the pile is thereafter lowered to slidably pass through the length of guide tube 22 and toward the Ocean floor. The length of pile is increased of course by adding further shorter lengths to the pile upper end as the pile by its own weight penetrates the ocean floor and is subsequently hammered to a desired depth. After the latter has achieved a suitable locking depth to support the platform and steady platform legs 11, the cement or grouting will be applied as above noted to the annulus 38 to form the peripheral seal between the pile and the collar. Grouting or cementing of the pile to collar 32 and the subsequent hardening of the cement rigidizing the structure into unitary member is an expedient well known in the art.

When platform 10 is operating in water depths approximating 700 to 1,000 feet, leg casing 21 will be immersed in the water such that the lower end is approximately 40 feet from the ocean bottom. It is understood that the actual physical properties of the composite leg structure will be such as to minimize the length and diameter of casing 21. However to be considered also is the limitation placed on the rigidity of the multiple piles which although adequate in compression, might not be sufiiciently rigid to produce a firm overlapping joint to transfer strain to the casing. The clamping arrangement shown in FIGURE 6 thus must be sufliciently rigid to effect the desired locking.

It is readily seen that the bulk, or the enormity of casing 21 as an economic factor, prompts its being salvaged for further use. This may be carried out in several ways by full utilization of the removable collar in the following manner.

If casing 21 in lowered position is located at a depth accessible to a diver, the latter may unbolt (FIGURE 2), or unclamp (FIGURE 6), collar 32 by removing clamp 53. Pile 31 may then be severed by an internally placed explosive at a point immediately beneath the lower end of the collar 32. Collar 32 is now disconnected and permitted to fall to the ocean floor as it is of no further use. The entire upper leg assembly including casing 21, tubes 22 and 23 and the upper ends of the respective piles may then be retracted to platform 10 in order that the latter might be moved to a new drilling spot. The imbedded end of the piles may thereafter be removed by severing from the ocean floor, or merely left.

The composite leg may be hoisted or floated to the water surface by floatation chambers either in the leg or separate thereto. A new collar 32 is now fastened to plate 24 to guide and preposition an incoming pile.

Should the casing 21 lower end, and subsequently collar 32 be at a water depth inaccessible to divers, the casing and major part of the piling might still be salvaged. Thus the piling would be explosively severed from the casing assembly as herein mentioned, thereby permitting the casing assembly to be floated to the water surface where the collar might be readily removed.

In an alternate arrangement of the leg as illustrated in FIGURE 3, the primary difference in structure as dis tinguished over what has been presently described is that the upper end of the removable collar is rigidly fastened to the lower end of the protruding guide tube rather than to the casing itself. In this instance, casing 56 includes a cross brace 57 adjacent to the casing lower end. Guide tube 58 is fixed to the cross brace 57 and extends therebelow, terminating at a wide flange 59.

Collar 61 also includes flange 62 from which depends body 63. Fastening means such as bolts or a circular, removable clamp 60, pulls the flanges into suitable engagement with sealing spacer 64 therebetween. The cement joint between collar 61 and pile 65, and method of supplying the same in this arrangement is substantially identical with the procedure described with respect to the foregoing seal shown in FIGURE 2.

In still another alternate embodiment as shown in FIGURES 4 and 5, the disposable locking collar is supported at both ends by the casing structure to give the cement joint greater rigidity. This is achieved by the disposable collar being adapted to be connected at opposed ends to a rigid face. In FIGURE 4, casing 71 follows closely the general elongated configuration of the previously described casings. The lower end is provided with a relatively heavy transfer plate or bracket 72. As previously noted, the use of a bracket fixed transversely in a casing is dependent on the function of the plate. That is, should it be desired that the collar holding area at the casing end be formed into a closed chamber, plate 72 would be fastened to the casing to form a watertight seal.

Plate 72 is provided with a plurality of through apertures or openings 74 each of which is adapted to receive a pile 75 which passes from the casing 71, to the ocean floor. Removable collar 73 is rigidly held within the collar chamber 87 at opposed ends of the collar. Further as noted, the holding means for securing the collar may take the form of a series of bolts at the collar flange or a removable clamp.

As shown in FIGURE 4, flange 76 at the upper end of collar 73 abuts a clamping boss 77 carried at the lower side of upper plate 78. A removable circular clamp 79 engages the mating flanges 76 and 77, holding them in rigid engagement. The lower end of collar 73 is similarly provided with a radial flange 81 which bolts directly to the inner face of plate 72, or to an adapter on said face, by a series of circularly arranged bolts 82. An adjustable spacer 83 compressed between flange 81 and plate 72, permits collar 73 to be properly fitted within the clamping space defined by flange 77 and face of plate 72. The arrangement and function of the peripheral grout seal rings 84 and 86 has been described with respect to the previously noted embodiments of the invention and need no further elaboration here since they follow a similar arrangement and function.

With respect to the means for assembling collar 73 to the casing 71, this may be achieved While the casing is under water, although preferably before it has been submerged. In either instance, casing 71 is provided with one or more side apertures communicated with chamber 87, which apertures may be covered with a bulkhead or the like to permit access to said chamber. Thus removable collar 73 is readily disconnected from its end held position at plate 72 and boss 77, by unbolting or unclamping. The collar with its inner cement seal and length of piling of course is of no further use and is disposed of. For separating collar 73 from the piling 75, both collar and pile might be severed adjacent to rings 84 and 86, beyond the cement joint. The entire leg, less pile 75, is now withdrawn from the ocean bottom.

In the embodiment of the structure shown in FIGURE 5, the disposable collar is removably clamped at opposite ends to spaced apart sections of the guide tube. Here leg casing 92 includes spaced cross brackets 93, 99 and 94 which, with the casing wall, defined collar chamber 96. Guide tubes 97 and 98 are supported longitudinally of casing 92 by a plurality of spaced apart brackets 99. Brackets 99 may as previously noted, take the form of water tight bulkheads so that chambers defined intermediate the successive brackets will provide a series of evacuable flotation chambers either for regulating the position of the casing or for storing oil. Sleeve ring 100 includes a cylindrical body 101 defining a central passage 102 arranged in axial alignment with guide tube 97.

Axial passage 102 slidably receives pile 103 which extends from the lower end thereof toward the ocean floor. A flange 104 depending from the upper end of body 101 is adapted to receive the clamping jaw of circular clamp 106. This latter member as previously noted engages and positions the respective flanges 104 and 107. In a similar manner, the upper end of collar 91 includes a second flange 108. The latter abuts and mates with flange 109 carried at the lower extremity of guide tube 97 to receive clamp 110.

Adjustable spacers 95 and 95' disposed at one or both ends of the respective collar flanges permit collar 91 to be tightly fitted between the receiving flanges 104 and :109. The nature of the engagement between collar 91 and the guide tube portions need not constitute a liquid tight fit since the unit includes rings 111 and 112 which define the annular sealing section wherein hardened cement forms a pile connecting annulus. Cement carrying lines 113 and 114 connect with the annulus 116 formed between rings 111 and 112 to regulate forming of the elongated cemented joint. The size of chamber 96 is such as to allow for a sufficiently long collar 91 as to provide a structurally acceptable grouted connection between pile and pile guide. In this respect, the chamber 96 can be up to 30 to 40 feet in height between plates 93 and 94 to easily accommodate a removable collar 91. Thus chamber 96 may be provided with one or more cut out sections to permit access to the chamber for removal and replacement of collars.

The order of magnitude of the presently described composite leg is such as to be beyond the capacity of many barge derricks and similar equipment which would be required to tend a platform including such legs. A desirable feature of the disclosed support legs then is the feature incorporated therein for adjusting from an upright position to a horizontal or floating attitude by utilizing buoyancy of the legs. The latter might thus be provided with buoyancy tanks formed integral with the leg or disposed externally thereto. As noted herein, the guide tube support members disposed transversely of the casing may comprise water tight bulkheads defining a series of controlled flotation chambers. These of course would be com municated to suitable piping for regulating the condition of the respective chambers with oil, water, or evacuated by air pressure to raise the casing to the water surface.

Obviously many modifications and variations of the invention, as hereinafter set forth, may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. Support and anchor leg for an offshore platform adapted to maintain the latter in a position above an ocean floor and including:

(a) an elongated casing having opposed upper and lower sections, said upper section being operably connected to said platform;

(b) at least one guide tube means fixedly positioned internally of said casing and extending longitudinally thereof;

(c) a pile having a portion of the length thereof disposed in said at least one guide tube means, said pile having another portion protruding from said guide tube means lower end, being adapted to be forced therefrom for insertion into an anchoring medium;

(d) a collar, removably connected to said guide tube means lower end and including; a cylindrical body aligned coaxial with said guide tube means and enclosing a portion of said pile, said body having an inner wall spaced outwardly from said pile to define an annulus therebetween; and

(e) a fastening means forming a connection with said pile and said collar at said annulus to rigidly fix said pile to said guide tube means, whereby when said pile is firmly imbedded in said ocean floor, said support leg may be separated therefrom for moving said platform, by disconnecting said collar from said guide tube means lower end.

2. In a support and anchor leg as defined in claim 1 wherein said guide tube means includes; a plurality of elongated guide tubes positioned internally of said casing, at least one pile extending through at least one of said plurality of guide tube ends, and having said removable collar connected thereto.

3. In a support and anchor leg as defined in claim 1 wherein; said fastening means forming a connection with said pile includes a hardened annular seal formed of a flowable material.

4. In a support and anchor leg as defined in claim 1 wherein said at least one guide tube means includes; a plurality of longitudinally extending guide tubes, fastened to each other and to the inner wall of said casing, said respective guide tubes having the lower ends thereof disposed adjacent said casing lower section.

'5. In a support and anchor leg as defined in claim 1 wherein said collar cylindrical body is supportably positioned at one end thereof in axial alignment with said guide tube means, the body other end extending downwardly from said casing toward the ocean floor.

6. In a support and anchor leg as defined in claim 1 wherein said cylindrical body is supportably positioned at opposed ends thereof in axial alignment with said guide tube.

7. In a support and anchor leg as defined in claim 5 wherein said elongated casing includes a transversely positioned plate at the lower end thereof, and said collar includes a radial flange removably connected to said plate.

8. In a support and anchor leg as defined in claim 7 including clamping means engaging said respective collar and guide tube flanges, to hold said collar and guide tube flanges in abutting engagement.

9. In a support and anchor leg as defined in claim 5 wherein said elongated casing will transversely position plate at the lower end having an opening therein, said guide tube means being registered in said opening and having a flange on said guide tube means spaced from said plate, and clamping means removably connecting said respective guide tube and collar flanges into engagement.

10. In a support and anchor leg as defined in claim 9 wherein said clamping means positioning said respective plate and collar flanges in abutting relationship includes a plurality of bolts dispersed through said flanges.

11. In a support and anchor leg as defined in claim 9 wherein said clamping means includes a removable clamp peripherally engaging said respective flanges to hold the same in abutting relationship.

12. In a support and anchor leg as defined in claim 1 wherein said elongated casing includes spaced apart members extending transversely of said casing and connected to the inner walls thereof to define a collar chamber therebetween, said at least one guide tube means extending through one of said spaced apart members and opening into said collar chamber, said collar being removably supported at opposed ends thereof by the respective transverse members to position said collar in alignment with said guide tube means lower end.

13. In a support and anchor leg as defined in claim 12 wherein said casing includes a plurality of spaced apart 15 References Cited UNITED STATES PATENTS 10/1967 Manning 6146.5 12/1967 Koonce et al. 6146.5

JACOB SHAPI-RO, Primary Examiner US. Cl. X;R. 6153 

